Changes to common practice, laws, and accepted behavior in both the automotive and trucking industries has forced the shutdown of engines during stops. Shutting down a car or truck engine causes stress on the battery and starter motor, leading to weakened batteries and overall lower system performance. Harsh conditions such as extreme cold environments exacerbate the problem and may lead to outright battery failure and/or starter failure.
The number of shutdowns per day for an engine may depend on the vehicle architecture, vehicle use, etc. In general, there are two types of vehicle architectures: “local delivery” vehicles, which can have, for example, as many as 250 shut-off events per day, and “long haul” vehicles, which can have up to, for example, 25 shut-off events per day. These shut-off events create low voltage conditions on the vehicle's DC electrical bus, which result in higher power requirements from the on-board energy storage system. Low voltage conditions on the DC electrical bus can also stress other vehicle components, including Electronic Control Units (ECUs), relays, switches, and pumps.